The 425 Cadillac engine is "only" @ 40 lbs. heavier than a stock sbc. The heads are a bit restrictive in stock form & will require some porting in the intake ports especially. The stock exhaust manifolds are a bit "concave" due to clearance issues with the stock '77-'79 front upper control arms in the Cadillac cars that they originally came in. But like others have said, they will respond very well with the same "hot rod" work as the 472 & 500's do. To do the "Stroker 454" thing, first, a Caddy 500 crank (4.304") stroke is needed. Then, a set of Oldsmobile (mid to late '60's) 425 c.i. (6.998" long) the Olds 7" connecting rods will be needed also, along with a set of EGGE Machine Company .040" over Oldsmobile 350 pistons will be needed too. The stock Olds 350 pistons are 4.057", so + .040" makes them a 4.097" diameter. A stock Cadillac 425 bore is 4.082" so, with a .015" over sizing will bring the bore of a 425 Caddy engine to 4.097" So let's do some math here, 4.097 X 4.097=16.785409 X 4.304 = 72.2444 X .7854 = 56.740751 X 8 = 453.926 rounded off to 454 c.i..

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No, you're wrong. The 425 Cadillac engines were produced by General Motors
from 1977 through 1979. They appear to look almost identical to the 472 & 500 c.i. engines that were produced from 1968 through 1976. The 425's shared the same engine code as the 500 c.i. engines, that be; "S" code for the carburetted
versions. Check with Cadillac history before assuming something that's not correct. The 429's were produced from the early 1960's through 1967, not at all
the same as the 425's!

When I saw the recommendation for Egge pistons, a "red flag" went up. While Egge makes a decent product, and one can certainly get them to make stuff nobody has made in 40 years, using them for Olds or any other "modern" application piston could be far more expensive than it appears. We do a lot of "mix and match" with bores, strokes and rod lengths. For less money, one can have "custom" forgings using better techniques. Speed Pro and Icon also offer a good forging for reasonable money for the Olds piston.

Bear with me for a moment. Consider this: Using your existing 425 crank, you can offset-grind to the desired 4.3" stroke (we're not gonna quibble over .003" here) and end up with a VERY desirable 2.2" rod journal (BBC). The Caddy cranks are good nodular units, so this will not weaken it significantly, and if the radii are ground properly, will actually strengthen it. Using the Eagle CRS7100C3D rod (narrowed back to BBC size) and a "custom" piston (of what ever bore size you desire) with a pin height of 1.52" will put you right there, with MUCH better parts for about the same money. The BBC rod bearing is .060" or so "wider" than the Cad, but narroweed bearings are readily available.

After looking at the various combinations available with factory parts, I'm thinking a better approach might be a 500 block and 368 or 425 crank (4.255 x 4.03). That makes 467 CID with a "big" bore and shorter stroke.

There are many performance parts available for the Cad these days, as it's a popular engine among the "claimer" roundy-round crowd.

I asked for detailed info on the history, (or time line) on the production run on all Cadillac V-8 engines, what sizes, when they were made & what cars did they get put in. Well, I got referred to a couple of web cites, one being Wikipedia. That one has all of the Cadillac V-8 engines listed. The 429 c.i. was produced from 1964 through 1967 & it was of the same (basic) design as that of the 390 c.i.. Then, (because of design & casting molds getting worn) Cadillac introduced the 472 in 1968. Two years later, the 500 started production. It wasn't untill AFTER 1970 that Cadillac started to "code" their engines with a single letter code. The 500 c.i. were all "coded" with an "S" code. Then, because of a government ordered "mandate" in 1976, the next year production of all American full size cars had to be "downsized". That included the engines. So, Cadillac started producing the 425's. Those were coded either an "S" or "T" code, "S" for carburetted, "T" for fuel injected. Then, when 1980 came about, The 425's were considered "too large" & That's why Cadillac started making the 368. The 368 looks allot like the 425-500's but internally are quite different. Especially after 1981 when the V-8/6/4 idea
came out. That didn't work well at all. So, then a totally different Cadillac engine went into production that wasn't anything close to the engines that were before that.
Now, as for the (1979) 425 Cadillac getting "Stroked" or "morphed" into a 454 c.i. engine, I decided that I was going to have to "go it alone" without the
assistance of people who "claim" to be supportive of all things Cadillac.
I did read some older "threads" about the use of Oldsmobile parts in a Cadillac
engine & most did say that it can, & has been done many times in years past,
but never heard of anyone doing that to a (late '70's) 425 Caddy engine. But,
now, there's at least a couple of people (I being one of them) that's willing to
try that. So far, I've collected a crank from a junk yard 500 block, a set of
mid '60's Olds 425 connecting rods & the intake manifold from the same "junk yard" 500 block. I've also bought a set of "Hell's Gate" brand header flanges
& two pair of Ford 351/400 m headers for re-shaping to fit the Caddy flanges
as the Caddy engines aren't "oriented" the same as the rest of the G.M. V-8
engines were back then. The Caddy engines were more like Fords than Chevy,
Pontiac, or Oldsmobile. Buick V-8's were very close to the Caddy engines though. The Buick 455's were almost the same as that of the Caddy 472 & 500's. Now, back to the "Stroked" 425 Caddy. I just recently bought a Chevy
big block 8 quart 454 truck oil pan to "modify" by cutting the gasket flange off
just below the top edge, then, do the same to a Cadillac mid sump oil pan, (one of the most common styles of Cadillac oil pans) then, re-welr the Caddy oil pan's gasket flange onto the Chevy oil pan so that I can have an oil pan
that'll allow me to install the Caddy engine into a Chevy car chassis. I also
know that I'll have to buy a new oil pick up tube that's originally designed for
a late '60's through late '70's El-Dorado in order to have the pick up centered into the oil pan's "sump". I have yet to order the pistons & their related parts,
but that's soon to happen.
Well, that's "it" on the project for now, so, later

In reply to "Mr. P-Body", If I'm reading you correctly, it sounds as if you're trying talk me into "de-stroking" & "going" bigger in cubic inches. I'm actually wanting to increase the stroke, but not any more than what Cadillac did with
the stock 500 c.i. engines. More stroke=more torque. Then your next question was, why I want to use a smaller engine block if I had a 500 block. The 500 block was cracked in the area of the "driver's side" motor mount & down that
side of the block above the oil pan. But that wasn't the only thing wrong with that block, one of the pistons broke the two compression rings & one of those
gouged a rather deep grove into the cylinder wall & locked that piston up, (& the entire engine was "stuck" because of that. That's why the car it was in was in the junk yard. I bought that 500 just for the parts that I "salvaged" from it, as it was from a "U-Pull-It" yard & engines were "on sale" the week that I bought it.
As for the reason for the EGGE brand of parts, if something was wrong with them, why are the guys at MTS using them? Also, that company's been in business almost as long as there have been cars around. (allot longer than I have). I do (however) agree with you that their parts are a bit on the "historic" side as they don't make parts for engines newer than 1980. And, using pistons that were made for another engine than the one that I'm going to be putting them into will cause me to have to "mill the deck" quite a bit to get a good "quench" or a decent compression ratio out of it, is a bit on the
costly side, but I've already got "into" it & cannot afford to change "horses"
now that "the race has started". And, besides that, if I don't "go for it" & stop
now, I do have another complete (untouched) bone stock (1978) 425 sitting
in my back shed. But, I've been wanting to do a "Caddiolds" 454 for years. I planned it out & have been told by quite a few people that it can be done, just not really needed to be done. Also, I want to keep the "cubes" no bigger
than 454". After all, that's the "stock" size of the most common of the Big Block Chevy engines, & this is going into a Chevy car. I didn't want to use a Chevy 454 because those are heavier than a Caddy engine, must be revved higher to get to the same power as that of A well built Caddy, they aren't cheap to get anywhere, & I'd have to do allot of front suspension parts swapping & alignment work to accommodate a "Rat motor" 454 engine. The car that I have was originally a 307 sbc car. That engine doesn't run & would
cost allot to get it running as the rings are stuck to the pistons from many years of sitting in a barn. And the valve seals are all rotted out too. Most everyone who's ever "messed around" with the late '60's Chevy 307's know that those weren't anything worth working on when something went wrong with them. Like the mid '70's Chevy 305's, they work OK at best when nothing 's wrong with them, But once something goes "amiss" then it's "best" to replace them with something better. So, being that a Cadillac engine only weighs @ 40 lbs. more than a small block "Chebbie" & the 425 Caddy engine
is told to be @ 100 lbs. lighter than that even, well, that makes swapping one in where a 305,307 or 350 was, a "piece of cake", (other than the motor mounts & oil pan" other than those, it's practically a "drop in". In 1973 - 1987
Chevy & G.M.C. trucks, even easier. The only thing needed to do there is, move the motor mount plates that are bolted to the truck's frame @ 4" forward & maybe the right exhaust manifold will need a slight "trimming" to clear the frame. I know that because I did that with a 1979 Chevy one-ton
truck & the 425 Caddy engine that I'm rebuilding into the "Stroker 454".

I don't understand the thinking here. Seems like a lot of time and money to make a 454 out of a 425 Cad engine, when it would have been cheaper and easier to just buy a 500 Cad and drop it in.
I'd rather have a 500 Cadillac than a reworked 425 to make 454 c.i. And if weight is your main consideration, then I'd spend the money on a pair of aluminum heads to bolt on a Chevy 454 and use that to save weight. A 454 with aluminum heads will be lighter than the 425 Caddy.

I don't understand the thinking here. Seems like a lot of time and money to make a 454 out of a 425 Cad engine, when it would have been cheaper and easier to just buy a 500 Cad and drop it in.
I'd rather have a 500 Cadillac than a reworked 425 to make 454 c.i. And if weight is your main consideration, then I'd spend the money on a pair of aluminum heads to bolt on a Chevy 454 and use that to save weight. A 454 with aluminum heads will be lighter than the 425 Caddy.

You chevy guys are all the same! You think chevy is the only way. A 425 Caddy is about 60lbs lighter than a BBC. So how much weight are you going to save by going with aluminum heads on the belly button engine?

You chevy guys are all the same! You think chevy is the only way. A 425 Caddy is about 60lbs lighter than a BBC. So how much weight are you going to save by going with aluminum heads on the belly button engine?

Bill

No, I did not tell him "Chevy is the only way". I suggested a 500 Caddy is a better choice, and since his post is revolving around the 425 being lighter than a 454 Chevy, I suggested he save both weight and money with an aluminum head 454. If that gets your tidy whiteys in a bunch, it's how you read it, not anything else.
The weight savings per head is 50 lbs., so it's 100 lbs less with aluminum heads vs. cast iron in a BBC. So 40 lbs. lighter than the non belly button 425 Caddy.
You Chevy haters are alwways looking for a reason to knock a Chevy engine, big or small.

I also don't understand all the work to build a 425 into a 454 but as I always say..... to each his own. Here's my 507" Cadillac that I've shown before to non-believers. I did a lot of head work with larger SS valves, shaft mounted roller rockers, 228/235 dur. cam, single plane int. with Quick Fuel 780 vac. sec.carb but it's still only 8.7:1 compression. We dyno'd it on 89 oct. gas, 466 hp @ 5,000 and 535 torque @ 4300......got about $6700 in it total

I understand what some have said, but, the main reason for my choice of a 425 Caddy is, I already have it. I've had the engine since 1998 & I bought the whole car that it was in for $125 in running & "drive-able" condition as a "parts car". Also, for me to buy even a "core" 454 Chevy engine would be quite expensive. The cheapest 454 Chevy that I've found within 250 miles from my house is being "offered" at $800 & that doesn't include the cost of getting it & bringing it home.
So by the time I got that "core" 454, got it home & looked it over, I would already have well over $1,000 into it. Way too expensive! And, like someone had already said, even with a pair of aluminum heads ($$$), a 454 Chevy is still heavier than a stock 425 Caddy. Also for those who keep suggesting that I get a 500 Caddy, that too is too expensive. The cheapest "core" 500 that's in pieces is "for sale" at $650 & it is over 150 miles from my house. Again, too much to invest just to start over. I can use the money spent on that, towards the machine shop charges on my already existing 425 Caddy engine.
I hope that explains my reasoning for doing what I'm doing with a 425 Caddy engine.

I understand what some have said, but, the main reason for my choice of a 425 Caddy is, I already have it. I've had the engine since 1998 & I bought the whole car that it was in for $125 in running & "drive-able" condition as a "parts car". Also, for me to buy even a "core" 454 Chevy engine would be quite expensive. The cheapest 454 Chevy that I've found within 250 miles from my house is being "offered" at $800 & that doesn't include the cost of getting it & bringing it home.
So by the time I got that "core" 454, got it home & looked it over, I would already have well over $1,000 into it. Way too expensive! And, like someone had already said, even with a pair of aluminum heads ($$$), a 454 Chevy is still heavier than a stock 425 Caddy. Also for those who keep suggesting that I get a 500 Caddy, that too is too expensive. The cheapest "core" 500 that's in pieces is "for sale" at $650 & it is over 150 miles from my house. Again, too much to invest just to start over. I can use the money spent on that, towards the machine shop charges on my already existing 425 Caddy engine.
I hope that explains my reasoning for doing what I'm doing with a 425 Caddy engine.

I understand how building a hot motor from another, non-chevy brand can be cheaper initial investment. People pay crazy money for bbc and sbc nowadays. I'd rather build an Olds than a Chevy any day... But that inexpensive initial investment is going to be offset by whatever I have to spend on it later, and I recognize that. You're going to have more money in your rotating assembly than it would cost to just get a decent 472 or 500, and your going to come up short in cubes too... I commend you for being different, though.

I used to play around with this sort of stuff. You can build a 470 cubic inch RB Mopar by using BB Chevy rods, offset grinding the crank to the BBC journal size and boring the pin end of the rods and cutting the cylinders to receive 429 Ford pistons.

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